The turbo on my 2000 Aero seems to work only when it wants to. It's intermittant and kicks in late on acceleration and then only for a few seconds. Sometimes its totally there and sometimes its not. Can't visibly see anything wrong. The linkage is intact and there are no visible vacuum leaks from any of the APC hoses. I did the bolt mod 2 years ago and its been working fine until this month. Ideas anyone?